Display technology is currently dominated by cathode-ray-tube (CRT) displays and liquid crystal displays (LCDs). Although CRT displays are well understood and typically inexpensive to manufacture, LCDs have advantages in power, size and safety. Extensive research in LCD technology has led to the development of large, high-resolution displays using addressable matrix scanning techniques and, more recently, active matrix techniques. Using either technique, narrow band or full color LCDs can be fabricated.
Presently, industry-standard color LCDs are fabricated using one of several technologies. A common approach involves the formation of pixel triads on the CMOS, BICMOS, NMOS, or other microcircuit substrate (e.g., silicon) to achieve full color (see FIG. 1). More specifically, each pixel is replicated three times, and a mosaic of red blue and green gel filters is placed over each pixel triad. A transparent conductor is deposited on the inside surface of a cover layer. Spacers are applied to either the substrate or the cover layer, and the two are bonded together. The region between the substrate and cover layer is filled with liquid crystal material. Polarizers may also be laminated over the cover layer.
Because pixel triads are used, the resolution of the display is decreased by a factor of three. Moreover, the transmitted light through the liquid crystal region passes through the polarizers and color filters, typically reducing the incident illumination to four percent (4%) or less. Thus, this approach can be regarding as an inefficient solution to generating a high-efficiency, color display. While slight improvements are under development using subtractive color filters and dichroic combiners, the expected efficiencies only approach twelve percent (12%).
Another approach for making color LCDs involves the use of filters formed from diffraction gratings. However, color microdisplays with diffraction-based pixels and convenient methods for manufacturing such displays inexpensively are not previously known.